1. Field of the Invention
The present invention relates to a copying machine, and more particularly to a copying machine comprising means for cancelling a saving power mode automatically.
2. Description of Related Art
In general, in a copying machine, detectors which detect if a manuscript is in place or not, if a manuscript cover is open or shut, if a manual paper feeding cover is open or shut, if a front cover is open or shut after maintenance, if a paper cassette is set, the size of papers which are set in the cassettes and so on, are arranged at each respective position. In an electrophotographic copying machine comprising an image video forming device which uses toner, the copying operation is performed as follows. The toner material is electrostatically attracted to an electrostatic latent image corresponding to the image of the manuscript to be copied, transferred imagewise to a copying paper, and the toner image formed on the paper is fixed. In the fixing operation, the copying paper is passed between two heating rollers heated at a constant temperature by a heating lamp, and the paper and toner are heated and pressed, fixing the toner image. During the copying operation it is necessary that the heating rollers be kept at a predetermined temperature of about 200 degrees Centigrade which is defined by the summation of a normal fixing temperature at which the toner can be fixed on the copying paper and a compensation temperature for compensating for temperature drop due to consecutive copying operations. In order to control the temperature of the heating rollers, the time for turning on the heating lamp is controlled by a thermister sensing the temperature of the heating rollers, and a temperature control circuit. It takes a few minutes to increase the temperature of the heating rollers from room temperature to the predetermined temperature after turning on the main switch of the copying machine and turning on the heating lamp at the beginning of the copying operation. In the above copying machine, whenever the copying operation is completed, the main switch may be turned off, and whenever the copying operation is started, the main switch may be turned on. With the above operation, it takes a long time to heat the heating lamp to the desired setting temperature (the process is called the warming phase), and the working efficiency of the copying machine could be decreased. To the contrary, with the main switch always turned on it is always possible to begin to operate the copying machine immediately, however, the cost of the copying operation may go up because of increasing the power consumption. For this reason, in order to reduce the warming up time and save on power consumption, there may be provided a power saving mode in the copying machine in which the thermister and the temperature control circuit control the heating lamp to keep the heating rollers at about 100 degrees Centigrade, and also there may be a switch for selecting the power saving mode during the operation phase of the copying machine. A timer which counts the waiting time of the copying operation may be provided. The power saving mode can be enabled when a constant time has passed during the waiting condition of the copying machine when the copy button for starting the copying operation has not been pressed with the main switch turned on, or when the power saving mode switch is pressed. On the other hand, when the instant power saving mode switch is turned off or when the copy button is pressed, the power saving mode can be canceled.
However, in the conventional copying machine provided with the capability to select a power saving mode and cancelling thereof, it is necessary for an operator to turn off the power saving mode switch or turn on the copy button for effecting the copy. Therefore, the copying operation is complicated. As one example, assuming that an operator fails to turn off the power saving mode switch, that is, without cancelling the power saving mode prior to the following operations such as setting the number of copies to be made, setting the magnification in the copying machine, placements of the manuscript to be copied, changing the cassette of the copying paper and so on, the time of the copying operation may be extended since the warming up operation of the heating rollers starts after these operations. Also, it is a drawback of the conventional copying machine that it might be necessary to operate these plural operations many times before starting the copying operation, resulting in considerable loss of time.